The adult dosage of penicillin is discretionary according to the type of disease, treatment modality, and weight range of the patient, and can be broadly categorized into intramuscular and oral agents according to the mode of penicillin administration. For intramuscular penicillins, the regular dosage for adults ranges from 400,000-800,000 units per dose. For oral penicillins, the usual dosage range for adults is 120mg-500mg/dose. There is some variability in dosage depending on the type of causative organism and the degree of infection. Under normal circumstances, the higher the concentration of pathogenic bacteria in the patient’s body, the dose of penicillin medication will be correspondingly higher. Pneumococcus, Candida albicans and other specific pathogens, compared with the staphylococcus aureus, gram-negative bacilli and other conventional pathogens in the use of drug dosage is also relatively large. The patient’s body weight is also an important reference factor in the use of penicillin drugs, in order to use the drug safety can be in the doctor and the pharmacist’s help to use the drug.